中文摘要 台灣地區水文、地理及氣象因素特殊，模式之建立必須能隨地區之特性的不同加以考慮，並依水體特性建立適合的水質模式。 本研究之模擬模式主要採用美國陸軍工程師團水道試驗所（Waterway Experimental Station，U.S. Army Corps of Engineer）所發展之CE-QUAL-W2二維水理、水質模式，作為分析之工具，以石門水庫為研究範圍，做二維水質模擬。將水庫視為體積可變的水體，考慮污染物質的流入、流出、沈降與消失，最後可得水溫與污染物質隨時間之分佈，並討論其變化趨勢。 CE-QUAL-W2模式主要模擬葉綠素a、氨氮、硝酸氮、總磷與溶氧等五個水質項目。由研究結果得知，CE-QUAL-W2水質模擬結果尚稱良好，可掌握整體變化趨勢，惟在豐水期來臨時，水庫之水質濃度有稍高之趨勢。 而水庫的水溫變化，不僅影響了流場的變化，更嚴重影響了水庫水質的變化。水庫中流場之變化與水庫出流量較無關係，流場之變化主要是由於夏季至冬季季節變化時，溫度下降，分層現象逐漸消失，以致流場產生劇烈翻滾現象，使得水庫流場變化較為劇烈。 ABSTRACT According to the particular factors of hydrology, geography, and meteorology, building a proper water quality model should consider with the local characteristics and water identity. This study analyzes the water quality simulation of Shih-Men reservoir, bases on the CE-QUAL-W2 developed by Waterway Experimental Station, U.S. Army Corps of Engineer. Assuming the volume of reservoir changing with time and taking into account of drift, settling, and disappearance of pollution, the relationship of water temperature and pollution distribution is discussed. One can safely state that, CE-QUAL-W2 can get the trend of water simulation variation. Just only wet period comes, the concentration of water quality in the reservoir get higher. In conclusion, the change of water temperature of reservoir not only affects the change of fluid dynamic but also greatly worsens the water quality. There is only a slight relationship between the change of fluid dynamic and the quantity of water draws off in usual. Nevertheless, the descending temperature and disappearing stratification during the transient between summer and winter leading to severe overturn in reservoir generates sever change of reservoir fluid dynamic.